Methodology for construction of Vulcan model of the Saltby Volcanic Formation, DGSM Nottingham-Melton project

Abstract

The object of constructing the Vulcan model was to create a quantitative 3-D visualisation of the concealed Saltby Volcanic Formation (SVF) (Carboniferous) within the area covered by the Nottingham and Melton Mobray 1:50 000 scale geological sheets (Nos. 126 and 142) which forms part of the current (2003) DGSM Nottingham-Melton Project. The model was not intended to be a structural geological representation; rather, a lithostratigraphic visualisation 'normalised' to an arbitrary horizon related to the (near) time-plane represented by the A. vanderbeckei Marine Band. This is a common concept in 2-D stratigraphic crosssections and fence diagrams, but an unusual application for the Vulcan 3-D modelling software. Once complete, the model would allow fully interactive rotation, visualisation and dynamic cross-sectional slicing in any orientation. The Vulcan model was developed in three versions from interpretations of borehole geophysical logs. Initially 8 boreholes were used, but as digitised geophysical logs from additional boreholes became available, successive Vulcan models were developed using 13, and finally, 26 boreholes. The modelling methodology was refined in each version, building on what had gone before but, as later versions included boreholes situated within the envelope area of the previous versions, the earlier Vulcan models were not retained